Discuss various reactions that occur in solvay process in preparation of Na₂CO₃.

When CO₂ is passed into a concentrated solution of Brine saturated with ammonia ammonium bicarbonate is formed.
$2{\mathrm{NH}}_3+{\mathrm{H}}_2\mathrm{O}+{\mathrm{CO}}_2\to {\left({\mathrm{NH}}_4\right)}_2{\mathrm{CO}}_3$
${\left({\mathrm{NH}}_4\right)}_2{\mathrm{CO}}_3+{\mathrm{H}}_2\mathrm{O}+{\mathrm{CO}}_2\to 2{\mathrm{NH}}_4{\mathrm{HCO}}_3$
Ammonium bicarbonate then react with sodium chloride forming sodiumbicarbonate.
${\mathrm{NH}}_4{\mathrm{HCO}}_3+\mathrm{NaCl}\to {\mathrm{NaHCO}}_3+{\mathrm{NH}}_4\mathrm{Cl}$
Precipitated sodiumbicarbonate is removed by filtration and changed into sodium carbonate by heating
$2{\mathrm{NaHCO}}_3\stackrel{\mathrm{\Delta }}{\to }{\mathrm{Na}}_2{\mathrm{CO}}_3+{\mathrm{H}}_2\mathrm{O}+{\mathrm{CO}}_2$
The filterate contains ammonium chloride it is mixed with Ca(OH)₂ and heated with steam
then NH₃ is liberated.
$2{\mathrm{NH}}_4\mathrm{Cl}+\mathrm{Ca}(\mathrm{OH}{)}_2\to 2{\mathrm{NH}}_3+{\mathrm{CaCl}}_2+2{\mathrm{H}}_2\mathrm{O}$